News and notes from the bleeding edge of Revelation Software development

Monthly Archives: April 2018

One of the changes we wanted to make with EditTables in v10 was to expose all of their runtime functionality easily through the normal property/method API. Some of this was already available in previous versions, but usually involved a method to set a plethora of style bits, which is not really satisfactory unless you’re a C++ programmer (as we have been reminded by various developers on several occasions!).

Besides the EditTable as a whole, there are essentially three other main programmable areas:

Columns

Rows

Cells

Providing unique properties and methods to address the capabilities of these areas is not really practicable, as it leads to an “explosion” of property names: For example, accessing the “text” associated with each of these would require three new properties such as:

COLUMNTEXT

ROWTEXT

CELLTEXT

Of course that’s only three, but considering that each of the aforementioned areas has something like 30 properties, you would suddenly add 90+ new property names to the product! Bear in mind also that columns, rows and cells each have many properties like TEXT in common, so a new name for each of these seems extremely wasteful and unnecessary.

(We could also have used something similar like the existing TEXTBYPOS method to achieve this, but then we’d have 30’ish new “BYPOS” methods instead, and methods aren’t properties anyway).

So, to keep the property namespace under control we decided to use this commonality and implement a set of “sub-objects” instead, one for each area. Unsurprisingly these are named:

COLUMNS

ROWS

CELLS

Each of these sub-objects are indexed and can be used to access a specific column, row or cell in the EditTable. They all share many common properties and methods, but also expose a few type-specific ones as well. As an example, this is how to set the CUEBANNER property for each sub-object:

The OpenInsight EditTable has always supported a set of cell-related common events that are fired when a user interacts with the control:

CHAR

CHANGED

CLICK

DBLCLK

OPTIONS

In order to process these events properly however, it is necessary to know which cell they relate to, and this can ostensibly be found by using the NOTIFYPOS property, which is set to the position of the cell that raised the event.

In theory this approach works well, but in practice it can exhibit problems: Events in OpenInsight are nearly always raised in an asynchronous fashion, which means that if two of those events where executed in quick succession for different cells, then NOTIFYPOS could be set to the position of the second cell, before the Basic+ event handler could process the event for the first cell, thereby leading to incorrect results.

In order to handle this better the EditTable now supports a series of corresponding “CELL” events:

CELLCHAR

CELLCHANGED

CELLCLICK

CELLDBLCLK

CELLOPTIONS

The only difference here is that these events pass the indexes of the cell that raised them as arguments to the event handler, thereby preserving their origin accurately.

Note that when a “CELL” event is defined the EditTable will non longer raise the ordinary event to prevent the notification from being processed twice.

(One useful example of the benefits of having the “CELL” events is that you can now use the new CELLCHANGED event for cell validation, rather than the usual POSCHANGED event, due to the fact that you know precisely where the change originated from. You also know that there actually was a change, rather than having to compare the cell’s current contents to it’s GOTFOCUSVALUE to discover this).

Support for deleting and inserting rows in the EditTable control has always been somewhat basic, exposing only minimum functionality that allows you to control how a user inserts or deletes a row in the grid. We’ve enhanced this for version 10 by providing some fine-grain control over the row insertion and deletion process that we’ll describe below.

Imposing limits

Firstly, a couple of new properties have been implemented that allow you to set limits on the number of rows a user can add or remove from the EditTable via the keyboard: These are the MAXROWLIMIT and MINROWLIMIT properties.

MAXROWLIMIT property

When MAXROWLIMIT is set the user cannot use the Insert key to insert more rows than the number specified by this property. The default value is “0”, which means there is no maximum limit. Note that this property does not apply to programmatic INSERT method operations or data set by the LIST or ARRAY properties.

MINROWLIMIT property

When MINROWLIMIT is set the user cannot use the Delete key to delete EditTable rows once the minimum limit has been reached. The default value is “0”, which means there is no minimum row limit. Note that this property does not apply to programmatic DELETE method operations or data set by the LIST or ARRAY properties.

Blocking the “Insert” and “Delete” keys

Previous versions of the EditTable allowed you to set a “Protected” property at design time that stopped all row insert and delete operations by the user. Unfortunately, this was not actually exposed run-time (unless you adjusted a bit-flag the control’s STYLE property), so in version 10 we’ve expanded the old “Protected” property into two new properties called ALLOWROWDELETE and ALLOWROWINSERT. These can used at both run-time and design-time.

ALLOWROWDELETE property

When set to False the user cannot use the Delete key to delete rows within an edit table. The default value of this property is True.

ALLOWROWINSERT property

When set to False the user cannot use the Insert key to insert new rows within an edit table. The default value of this property is True.

Managing the “Insert” and “Delete” keys

Finally, we made some changes to the way the actual inserts and deletes take place to give you an opportunity to intercept them for even more control. In previous versions of OpenInsight the EditTable notified you of an insert or delete operation after it had taken place, via the INSERTROW and DELETEROW events respectively. This means that if you wanted to ‘prevent’ the modification based on some run-time criteria you had to effectively undo it, which usually included some sort of unpleasant visual effect as the insert or delete was rolled back (it also resulted in a loss of formatting information or other cell-specific data that you would have to reapply).

In version 10 we’ve added a new Boolean property called ROWEVENTMODE. When set to False (the default) row insertion and deletion via the keyboard behaves in exactly the same way as previous versions of OpenInsight. When set to True however, the INSERTROW or DELETEROW event happens before the actual operation takes place, and at this point you can do the following:

If you’re using an EventScript you can return FALSE$ and the operation will be cancelled.

If you’re using a code called from a QuickEvent you can set the EventStatus flag in your code to prevent the operation from proceeding further, just as you would currently do in a WINDOWCLOSE event to cancel it.

E.g. Stopping a row being deleted in a DELETEROW EventScript handler.

// Assumes "RowEventMode" is "True"
//
// Check to see if there is anything in column 2 of the deleted data,// and if so stop the delete via the event return value.
$insert logical
if bLen( rowData<2> ) then
// Stop the delete
retVal = FALSE$
end else
retVal = TRUE$
end
return retVal

E.g. Stopping a row being deleted in a DELETEROW QuickEvent handler

// Assumes "RowEventMode" is "True"
//
// Check to see if there is anything in column 2 of the deleted data,// and if so stop the delete via the Event Status
$insert logical
if bLen( rowData<2> ) then
// Stop the delete
call set_EventStatus( TRUE$ )
end
return

Of course, once you’ve allowed the Insert or Delete operation to take place you may also want to do some post-processing, and for this we’ve provided two new events: INSERTEDROW and DELETEDROW. These have the same signature as their INSERTROW and DELETEROW counterparts and are executed after the row modification has taken place (Note that these are only fired if the ROWEVENTMODE is True).

It is also worth noting that, as with previous versions of OpenInsight, using the DELETE and INSERT methods to programatically modify the EditTable contents will not trigger the INSERTROW or DELETEROW events (or any subsequent INSERTEDROW and DELETEDROW events either).

One small (but useful!) feature we added to the Basic+ editor was the use of “region blocks” to help with code organization in large programs. The blocks group together related sections of code under a descriptive name so they may be navigated and handled more easily (those of you who have programmed in other languages such a C# and C++ might be familiar with this concept already).

Essentially region blocks are simply a pair of statements ( “#region” and “#endregion”) that you insert before and after a block of code to define it, along with a name that describes the region. Once you have done this the entire region becomes a “fold point”, so it can be folded to hide it, and it also appears as a “jump point” in the editor navigation dropdown so you can get to it quickly.